libutil/pw_util.c

   1 /*-
   2  * Copyright (c) 1990, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  * Copyright (c) 2002 Networks Associates Technology, Inc.
   5  * All rights reserved.
   6  *
   7  * Portions of this software were developed for the FreeBSD Project by
   8  * ThinkSec AS and NAI Labs, the Security Research Division of Network
   9  * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
  10  * ("CBOSS"), as part of the DARPA CHATS research program.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 4. Neither the name of the University nor the names of its contributors
  21  *    may be used to endorse or promote products derived from this software
  22  *    without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #ifndef lint
  38 #if 0
  39 static const char sccsid[] = "@(#)pw_util.c     8.3 (Berkeley) 4/2/94";
  40 #endif
  41 static const char rcsid[] =
  42   "$FreeBSD$";
  43 #endif /* not lint */
  44
  45 /*
  46  * This file is used by all the "password" programs; vipw(8), chpass(1),
  47  * and passwd(1).
  48  */
  49
  50 #include <sys/param.h>
  51 #include <sys/errno.h>
  52 #include <sys/time.h>
  53 #include <sys/resource.h>
  54 #include <sys/stat.h>
  55 #include <sys/wait.h>
  56
  57 #include <ctype.h>
  58 #include <err.h>
  59 #include <fcntl.h>
  60 #include <inttypes.h>
  61 #include <libgen.h>
  62 #include <paths.h>
  63 #include <pwd.h>
  64 #include <signal.h>
  65 #include <stdio.h>
  66 #include <stdlib.h>
  67 #include <string.h>
  68 #include <unistd.h>
  69
  70 #include "libutil.h"
  71
  72 static pid_t editpid = -1;
  73 static int lockfd = -1;
  74 static char masterpasswd[PATH_MAX];
  75 static char passwd_dir[PATH_MAX];
  76 static char tempname[PATH_MAX];
  77 static int initialized;
  78
  79 #if 0
  80 void
  81 pw_cont(int sig)
  82 {
  83
  84         if (editpid != -1)
  85                 kill(editpid, sig);
  86 }
  87 #endif
  88
  89 /*
  90  * Initialize statics and set limits, signals & umask to try to avoid
  91  * interruptions, crashes etc. that might expose passord data.
  92  */
  93 int
  94 pw_init(const char *dir, const char *master)
  95 {
  96 #if 0
  97         struct rlimit rlim;
  98 #endif
  99
 100         if (dir == NULL) {
 101                 strcpy(passwd_dir, _PATH_ETC);
 102         } else {
 103                 if (strlen(dir) >= sizeof(passwd_dir)) {
 104                         errno = ENAMETOOLONG;
 105                         return (-1);
 106                 }
 107                 strcpy(passwd_dir, dir);
 108         }
 109
 110         if (master == NULL) {
 111                 if (dir == NULL) {
 112                         strcpy(masterpasswd, _PATH_MASTERPASSWD);
 113                 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
 114                     passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
 115                         errno = ENAMETOOLONG;
 116                         return (-1);
 117                 }
 118         } else {
 119                 if (strlen(master) >= sizeof(masterpasswd)) {
 120                         errno = ENAMETOOLONG;
 121                         return (-1);
 122                 }
 123                 strcpy(masterpasswd, master);
 124         }
 125
 126         /*
 127          * The code that follows is extremely disruptive to the calling
 128          * process, and is therefore disabled until someone can conceive
 129          * of a realistic scenario where it would fend off a compromise.
 130          * Race conditions concerning the temporary files can be guarded
 131          * against in other ways than masking signals (by checking stat(2)
 132          * results after creation).
 133          */
 134 #if 0
 135         /* Unlimited resource limits. */
 136         rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
 137         (void)setrlimit(RLIMIT_CPU, &rlim);
 138         (void)setrlimit(RLIMIT_FSIZE, &rlim);
 139         (void)setrlimit(RLIMIT_STACK, &rlim);
 140         (void)setrlimit(RLIMIT_DATA, &rlim);
 141         (void)setrlimit(RLIMIT_RSS, &rlim);
 142
 143         /* Don't drop core (not really necessary, but GP's). */
 144         rlim.rlim_cur = rlim.rlim_max = 0;
 145         (void)setrlimit(RLIMIT_CORE, &rlim);
 146
 147         /* Turn off signals. */
 148         (void)signal(SIGALRM, SIG_IGN);
 149         (void)signal(SIGHUP, SIG_IGN);
 150         (void)signal(SIGINT, SIG_IGN);
 151         (void)signal(SIGPIPE, SIG_IGN);
 152         (void)signal(SIGQUIT, SIG_IGN);
 153         (void)signal(SIGTERM, SIG_IGN);
 154         (void)signal(SIGCONT, pw_cont);
 155
 156         /* Create with exact permissions. */
 157         (void)umask(0);
 158 #endif
 159         initialized = 1;
 160         return (0);
 161 }
 162
 163 /*
 164  * Lock the master password file.
 165  */
 166 int
 167 pw_lock(void)
 168 {
 169
 170         if (*masterpasswd == '\0')
 171                 return (-1);
 172
 173         /*
 174          * If the master password file doesn't exist, the system is hosed.
 175          * Might as well try to build one.  Set the close-on-exec bit so
 176          * that users can't get at the encrypted passwords while editing.
 177          * Open should allow flock'ing the file; see 4.4BSD.    XXX
 178          */
 179         for (;;) {
 180                 struct stat st;
 181
 182                 lockfd = open(masterpasswd, O_RDONLY, 0);
 183                 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
 184                         err(1, "%s", masterpasswd);
 185                 /* XXX vulnerable to race conditions */
 186                 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
 187                         if (errno == EWOULDBLOCK) {
 188                                 errx(1, "the password db file is busy");
 189                         } else {
 190                                 err(1, "could not lock the passwd file: ");
 191                         }
 192                 }
 193
 194                 /*
 195                  * If the password file was replaced while we were trying to
 196                  * get the lock, our hardlink count will be 0 and we have to
 197                  * close and retry.
 198                  */
 199                 if (fstat(lockfd, &st) == -1)
 200                         err(1, "fstat() failed: ");
 201                 if (st.st_nlink != 0)
 202                         break;
 203                 close(lockfd);
 204                 lockfd = -1;
 205         }
 206         return (lockfd);
 207 }
 208
 209 /*
 210  * Create and open a presumably safe temp file for editing the password
 211  * data, and copy the master password file into it.
 212  */
 213 int
 214 pw_tmp(int mfd)
 215 {
 216         char buf[8192];
 217         ssize_t nr;
 218         const char *p;
 219         int tfd;
 220
 221         if (*masterpasswd == '\0')
 222                 return (-1);
 223         if ((p = strrchr(masterpasswd, '/')))
 224                 ++p;
 225         else
 226                 p = masterpasswd;
 227         if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
 228                 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
 229                 errno = ENAMETOOLONG;
 230                 return (-1);
 231         }
 232         if ((tfd = mkstemp(tempname)) == -1)
 233                 return (-1);
 234         if (mfd != -1) {
 235                 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
 236                         if (write(tfd, buf, (size_t)nr) != nr)
 237                                 break;
 238                 if (nr != 0) {
 239                         unlink(tempname);
 240                         *tempname = '\0';
 241                         close(tfd);
 242                         return (-1);
 243                 }
 244         }
 245         return (tfd);
 246 }
 247
 248 /*
 249  * Regenerate the password database.
 250  */
 251 int
 252 pw_mkdb(const char *user)
 253 {
 254         int pstat;
 255         pid_t pid;
 256
 257         (void)fflush(stderr);
 258         switch ((pid = fork())) {
 259         case -1:
 260                 return (-1);
 261         case 0:
 262                 /* child */
 263                 if (user == NULL)
 264                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 265                             "-d", passwd_dir, tempname, (char *)NULL);
 266                 else
 267                         execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
 268                             "-d", passwd_dir, "-u", user, tempname,
 269                             (char *)NULL);
 270                 _exit(1);
 271                 /* NOTREACHED */
 272         default:
 273                 /* parent */
 274                 break;
 275         }
 276         if (waitpid(pid, &pstat, 0) == -1)
 277                 return (-1);
 278         if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
 279                 return (0);
 280         errno = 0;
 281         return (-1);
 282 }
 283
 284 /*
 285  * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
 286  * if it was not.
 287  */
 288 int
 289 pw_edit(int notsetuid)
 290 {
 291         struct sigaction sa, sa_int, sa_quit;
 292         sigset_t oldsigset, nsigset;
 293         struct stat st1, st2;
 294         const char *editor;
 295         int pstat;
 296
 297         if ((editor = getenv("EDITOR")) == NULL)
 298                 editor = _PATH_VI;
 299         if (stat(tempname, &st1) == -1)
 300                 return (-1);
 301         sa.sa_handler = SIG_IGN;
 302         sigemptyset(&sa.sa_mask);
 303         sa.sa_flags = 0;
 304         sigaction(SIGINT, &sa, &sa_int);
 305         sigaction(SIGQUIT, &sa, &sa_quit);
 306         sigemptyset(&nsigset);
 307         sigaddset(&nsigset, SIGCHLD);
 308         sigprocmask(SIG_BLOCK, &nsigset, &oldsigset);
 309         switch ((editpid = fork())) {
 310         case -1:
 311                 return (-1);
 312         case 0:
 313                 sigaction(SIGINT, &sa_int, NULL);
 314                 sigaction(SIGQUIT, &sa_quit, NULL);
 315                 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 316                 if (notsetuid) {
 317                         (void)setgid(getgid());
 318                         (void)setuid(getuid());
 319                 }
 320                 errno = 0;
 321                 execlp(editor, basename(editor), tempname, (char *)NULL);
 322                 _exit(errno);
 323         default:
 324                 /* parent */
 325                 break;
 326         }
 327         for (;;) {
 328                 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
 329                         if (errno == EINTR)
 330                                 continue;
 331                         unlink(tempname);
 332                         editpid = -1;
 333                         break;
 334                 } else if (WIFSTOPPED(pstat)) {
 335                         raise(WSTOPSIG(pstat));
 336                 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
 337                         editpid = -1;
 338                         break;
 339                 } else {
 340                         unlink(tempname);
 341                         editpid = -1;
 342                         break;
 343                 }
 344         }
 345         sigaction(SIGINT, &sa_int, NULL);
 346         sigaction(SIGQUIT, &sa_quit, NULL);
 347         sigprocmask(SIG_SETMASK, &oldsigset, NULL);
 348         if (stat(tempname, &st2) == -1)
 349                 return (-1);
 350         return (st1.st_mtime != st2.st_mtime);
 351 }
 352
 353 /*
 354  * Clean up.  Preserve errno for the caller's convenience.
 355  */
 356 void
 357 pw_fini(void)
 358 {
 359         int serrno, status;
 360
 361         if (!initialized)
 362                 return;
 363         initialized = 0;
 364         serrno = errno;
 365         if (editpid != -1) {
 366                 kill(editpid, SIGTERM);
 367                 kill(editpid, SIGCONT);
 368                 waitpid(editpid, &status, 0);
 369                 editpid = -1;
 370         }
 371         if (*tempname != '\0') {
 372                 unlink(tempname);
 373                 *tempname = '\0';
 374         }
 375         if (lockfd != -1)
 376                 close(lockfd);
 377         errno = serrno;
 378 }
 379
 380 /*
 381  * Compares two struct pwds.
 382  */
 383 int
 384 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
 385 {
 386         return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
 387             pw1->pw_uid == pw2->pw_uid &&
 388             pw1->pw_gid == pw2->pw_gid &&
 389             strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
 390             pw1->pw_change == pw2->pw_change &&
 391             pw1->pw_expire == pw2->pw_expire &&
 392             strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
 393             strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
 394             strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
 395 }
 396
 397 /*
 398  * Make a passwd line out of a struct passwd.
 399  */
 400 char *
 401 pw_make(const struct passwd *pw)
 402 {
 403         char *line;
 404
 405         asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
 406             pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 407             pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
 408             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 409         return (line);
 410 }
 411
 412 /*
 413  * Make a passwd line (in v7 format) out of a struct passwd
 414  */
 415 char *
 416 pw_make_v7(const struct passwd *pw)
 417 {
 418         char *line;
 419
 420         asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
 421             (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
 422             pw->pw_gecos, pw->pw_dir, pw->pw_shell);
 423         return (line);
 424 }
 425
 426 /*
 427  * Copy password file from one descriptor to another, replacing, deleting
 428  * or adding a single record on the way.
 429  */
 430 int
 431 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
 432 {
 433         char buf[8192], *end, *line, *p, *q, *r, t;
 434         struct passwd *fpw;
 435         const struct passwd *spw;
 436         size_t len;
 437         int eof, readlen;
 438
 439         spw = pw;
 440         if (pw == NULL) {
 441                 line = NULL;
 442                 if (old_pw == NULL)
 443                         return (-1);
 444                 spw = old_pw;
 445         } else if ((line = pw_make(pw)) == NULL)
 446                 return (-1);
 447
 448         eof = 0;
 449         len = 0;
 450         p = q = end = buf;
 451         for (;;) {
 452                 /* find the end of the current line */
 453                 for (p = q; q < end && *q != '\0'; ++q)
 454                         if (*q == '\n')
 455                                 break;
 456
 457                 /* if we don't have a complete line, fill up the buffer */
 458                 if (q >= end) {
 459                         if (eof)
 460                                 break;
 461                         if ((size_t)(q - p) >= sizeof(buf)) {
 462                                 warnx("passwd line too long");
 463                                 errno = EINVAL; /* hack */
 464                                 goto err;
 465                         }
 466                         if (p < end) {
 467                                 q = memmove(buf, p, end - p);
 468                                 end -= p - buf;
 469                         } else {
 470                                 p = q = end = buf;
 471                         }
 472                         readlen = read(ffd, end, sizeof(buf) - (end - buf));
 473                         if (readlen == -1)
 474                                 goto err;
 475                         else
 476                                 len = (size_t)readlen;
 477                         if (len == 0 && p == buf)
 478                                 break;
 479                         end += len;
 480                         len = end - buf;
 481                         if (len < (ssize_t)sizeof(buf)) {
 482                                 eof = 1;
 483                                 if (len > 0 && buf[len - 1] != '\n')
 484                                         ++len, *end++ = '\n';
 485                         }
 486                         continue;
 487                 }
 488
 489                 /* is it a blank line or a comment? */
 490                 for (r = p; r < q && isspace(*r); ++r)
 491                         /* nothing */ ;
 492                 if (r == q || *r == '#') {
 493                         /* yep */
 494                         if (write(tfd, p, q - p + 1) != q - p + 1)
 495                                 goto err;
 496                         ++q;
 497                         continue;
 498                 }
 499
 500                 /* is it the one we're looking for? */
 501
 502                 t = *q;
 503                 *q = '\0';
 504
 505                 fpw = pw_scan(r, PWSCAN_MASTER);
 506
 507                 /*
 508                  * fpw is either the struct passwd for the current line,
 509                  * or NULL if the line is malformed.
 510                  */
 511
 512                 *q = t;
 513                 if (fpw == NULL || fpw->pw_uid != spw->pw_uid) {
 514                         /* nope */
 515                         if (fpw != NULL)
 516                                 free(fpw);
 517                         if (write(tfd, p, q - p + 1) != q - p + 1)
 518                                 goto err;
 519                         ++q;
 520                         continue;
 521                 }
 522                 if (old_pw && !pw_equal(fpw, old_pw)) {
 523                         warnx("entry inconsistent");
 524                         free(fpw);
 525                         errno = EINVAL; /* hack */
 526                         goto err;
 527                 }
 528                 free(fpw);
 529
 530                 /* it is, replace or remove it */
 531                 if (line != NULL) {
 532                         len = strlen(line);
 533                         if (write(tfd, line, len) != (int)len)
 534                                 goto err;
 535                 } else {
 536                         /* when removed, avoid the \n */
 537                         q++;
 538                 }
 539                 /* we're done, just copy the rest over */
 540                 for (;;) {
 541                         if (write(tfd, q, end - q) != end - q)
 542                                 goto err;
 543                         q = buf;
 544                         readlen = read(ffd, buf, sizeof(buf));
 545                         if (readlen == 0)
 546                                 break;
 547                         else
 548                                 len = (size_t)readlen;
 549                         if (readlen == -1)
 550                                 goto err;
 551                         end = buf + len;
 552                 }
 553                 goto done;
 554         }
 555
 556         /* if we got here, we didn't find the old entry */
 557         if (line == NULL) {
 558                 errno = ENOENT;
 559                 goto err;
 560         }
 561         len = strlen(line);
 562         if ((size_t)write(tfd, line, len) != len ||
 563             write(tfd, "\n", 1) != 1)
 564                 goto err;
 565  done:
 566         if (line != NULL)
 567                 free(line);
 568         return (0);
 569  err:
 570         if (line != NULL)
 571                 free(line);
 572         return (-1);
 573 }
 574
 575 /*
 576  * Return the current value of tempname.
 577  */
 578 const char *
 579 pw_tempname(void)
 580 {
 581
 582         return (tempname);
 583 }
 584
 585 /*
 586  * Duplicate a struct passwd.
 587  */
 588 struct passwd *
 589 pw_dup(const struct passwd *pw)
 590 {
 591         char *dst;
 592         struct passwd *npw;
 593         ssize_t len;
 594
 595         len = sizeof(*npw);
 596         if (pw->pw_name != NULL)
 597                 len += strlen(pw->pw_name) + 1;
 598         if (pw->pw_passwd != NULL)
 599                 len += strlen(pw->pw_passwd) + 1;
 600         if (pw->pw_class != NULL)
 601                 len += strlen(pw->pw_class) + 1;
 602         if (pw->pw_gecos != NULL)
 603                 len += strlen(pw->pw_gecos) + 1;
 604         if (pw->pw_dir != NULL)
 605                 len += strlen(pw->pw_dir) + 1;
 606         if (pw->pw_shell != NULL)
 607                 len += strlen(pw->pw_shell) + 1;
 608         if ((npw = malloc((size_t)len)) == NULL)
 609                 return (NULL);
 610         memcpy(npw, pw, sizeof(*npw));
 611         dst = (char *)npw + sizeof(*npw);
 612         if (pw->pw_name != NULL) {
 613                 npw->pw_name = dst;
 614                 dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
 615         }
 616         if (pw->pw_passwd != NULL) {
 617                 npw->pw_passwd = dst;
 618                 dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
 619         }
 620         if (pw->pw_class != NULL) {
 621                 npw->pw_class = dst;
 622                 dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
 623         }
 624         if (pw->pw_gecos != NULL) {
 625                 npw->pw_gecos = dst;
 626                 dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
 627         }
 628         if (pw->pw_dir != NULL) {
 629                 npw->pw_dir = dst;
 630                 dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
 631         }
 632         if (pw->pw_shell != NULL) {
 633                 npw->pw_shell = dst;
 634                 dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
 635         }
 636         return (npw);
 637 }
 638
 639 #include "pw_scan.h"
 640
 641 /*
 642  * Wrapper around an internal libc function
 643  */
 644 struct passwd *
 645 pw_scan(const char *line, int flags)
 646 {
 647         struct passwd pw, *ret;
 648         char *bp;
 649
 650         if ((bp = strdup(line)) == NULL)
 651                 return (NULL);
 652         if (!__pw_scan(bp, &pw, flags)) {
 653                 free(bp);
 654                 return (NULL);
 655         }
 656         ret = pw_dup(&pw);
 657         free(bp);
 658         return (ret);
 659 }